A memory card serving as a card storage unit includes flash memory for a storage medium. The memory card is very small in size, and thus consumes very little electricity for data reading and writing. With such advantages, the memory card has been popular especially as recording medium typically for camera-equipped mobile phones and PDAs (Personal Digital Assistances).
Compared with disk storage units exemplified by flexible disks (FDs) and magneto-optic disks (MOs), the memory cards are smaller in storage capacity and higher in price. With the recent technological progress and economies of scale in manufacturing observed for devices using memory cards, however, the storage capacity of the memory cards is increased up to about 128 MB, and the price thereof is reduced.
Moreover, unlike FDs and MOs, the memory cards require no drive for data reading and writing. With such an advantage, the memory cards are considered preferable as storage media for digital cameras, notebook PCs, and portable music players those placing prime importance on power-thriftiness and portability.
The miniSD card has the outer dimensions of 21.55 mm (length)×20 mm (width)×1.4 mm (thickness). On the other hand, the SD card has the outer dimensions of 32.2 mm (length)×24 mm (width)×2.1 mm (thickness). As such, compared with the SD card, the miniSD card is reduced in capacity about 60%. Another difference of the miniSD card from the SD card is the number of connector terminals provided on the surface, i.e., 11 pins for the miniSD card and 9 pins for the SD card.
For data reading and writing from/to such a memory card, a memory card connector has appeared in the market to serve as a connector for the purpose. The memory card connector is provided with a lock mechanism to prevent a memory card inserted into a housing from being detached or pulled out. As an example, refer to JP-A-2003-86296.
The above memory card connector includes the housing, a shield plate which is attached as to cover the housing upper surface and both side surfaces, the lock mechanism for locking the inserted memory card, and a connector pin retention section formed in one piece with the housing. The lock mechanism includes a lock member which is provided for engaging with the memory card inserted into a memory card insertion section to lock the memory card at its predetermined insertion position, a slider for supporting the lock member, an ejection coil spring for biasing the slider in the pull-out direction, and a lock pin which is provided for engaging with a heart cam formed to the slider to latch the slider at its attachment position.
The problem with such a conventional memory card connector is that when the coil spring is increased in compressive strength to pull out the memory card against the friction force between the memory card and a plurality of connector pins (contact terminals) which is making contact with terminals of the memory card, the memory card might pop out from the memory card connector.